Gasket for a filtration element and module integrating a filtration element fitted with such a gasket

ABSTRACT

The invention provides a sealing gasket for mounting in a passage ( 5 ) of a support plate ( 4 ) to surround the end of a tubular-shaped filter element ( 3 ) provided with at least one fluid flow channel ( 3   1 ), the channel lying within a flow section Sc, the gasket being constituted in the form of a sleeve: 
         possessing a height h not less than the height hps of the passage ( 5 ) in the support plate ( 4 ); and    presenting an overlap bore ( 15 ) for the filter element ( 3 ) defined between one end ( 16 ) of the sleeve and a shoulder ( 17 ) which co-operates with the other end of the sleeve to define a channel bore ( 19 ) for the fluid, the shoulder ( 17 ) possessing a surface for acting as an abutment for the terminal portion of the filter element and presenting dimensions that are adapted to extend outside the flow section Sc so as to avoid impeding fluid circulation, the overlap bore ( 15 ) being provided with a groove ( 28 ) adjacent to the shoulder ( 17 ) in order to allow the gasket to creep.

The present invention relates to the technical field of molecular orparticulate separation using filter or separation elements generallyreferred to as membranes, adapted to separate molecules or particlescontained in a fluid medium for processing.

The present invention relates more particularly to technical meansadapted to provide sealing for such filter or separation elements.

The subject matter of the invention finds a particularly advantageousapplication in the field of filtering, in the broad sense, a fluidmedium for processing, and in particular nanofiltering, ultrafiltering,microfiltering, etc.

In the state of the art, it is known to use a filter module constitutedby a metal case fitted at each end with a support plate arranged topresent one or more packages for allowing filter elements of tubularshape to be positioned relative to one another. The filter elements thusextend inside the case parallel to one another and they are mounted inleaktight manner at each end to a support plate.

Each filter element has at least one flow channel for the fluid to beprocessed, the channel extending from one terminal portion to the otherterminal portion of the element. Filter elements perform cross-flowfiltering of the fluid in order to obtain, at the peripheral surface ofthe filter elements, an outlet filtrate that is designed to be recoveredin a collection volume situated between the support plates and the case.

In order to ensure sealing between the terminal portions of the filterelements and the support plates, sealing gaskets are positioned andclamped by means of a metal backplate fixed on each support plate. Thesealing gaskets are made of deformable material such as an elastomer ora rubber so that on being tightened they provide sealing between thesupport plates and the filter elements.

Unfortunately, it sometimes happens that filter elements are broken attheir terminal portions positioned in the support plates. The Applicanthas found that the main cause of filter elements breaking at the supportplates comes from friction between the filter element and the supportplate and/or the clamping back plate.

On the basis of that observation, the Applicant has developed a novelsealing gasket for a filter element that is designed to avoid theelements becoming eroded by contact with the support plates and/or theclamping backplates, without disturbing fluid flow.

The object of the invention is thus to propose a sealing gasket formounting in a passage of a support plate to surround the end of a filterelement of tubular shape that is provided with at least one flow channelfor a fluid, said channel lying within a flow section.

According to the invention, the sealing gasket is made in the form of asleeve:

-   -   possessing a height not less than the height of the passage in        the support plate; and    -   presenting an overlap bore for the filter element defined        between one end of the sleeve and a shoulder which co-operates        with the other end of the sleeve to define a channel bore for        the fluid, the shoulder possessing a surface for acting as an        abutment for the terminal portion of the filter element and        presenting dimensions that are adapted to extend outside the        flow section so as to avoid impeding fluid circulation, the        overlap bore being provided with a groove adjacent to the        shoulder in order to allow the gasket to creep.

The sealing gasket of the invention makes it possible to avoid anycontact between the filter elements and the metal portions constitutedby the clamping backplates and by the support plates. By implementing anabutment for the filter elements, the filter elements are prevented frommoving under the effect of the pressure difference that arises betweentheir upstream and downstream terminal portions, such that a filterelement can no longer move, and consequently can no longer come intocontact with the metal backplate.

Various other characteristics appear from the description given belowwith reference to the accompanying drawings which, as non-limitingexamples, show embodiments and implementations of the invention.

FIG. 1 is an elevation section view of an embodiment of a filter moduleusing a sealing gasket in accordance with the invention.

FIG. 2 is a transverse view looking substantially along lines II-II ofFIG. 1.

FIG. 3 shows a filter element fitted on each of its terminal portionswith a sealing gasket of the invention.

FIG. 4 is a transverse view on a larger scale seen looking substantiallyalong liens IV-IV of FIG. 3 and showing a characteristic detail of theinvention.

FIG. 5 is a view on a larger scale showing various characteristics of anembodiment of a sealing gasket of the invention.

FIG. 6 shows a multiple sealing gasket in accordance with the invention.

As can be seen more clearly in FIGS. 1 and 2, the subject matter of theinvention is implemented for a device or module 1 performing cross-flowfiltering for a fluid to be treated that can be of any kind. In a caseor cylinder 2, the module 1 comprises one, and more generally a seriesof tubular-shaped filter elements 3 extending parallel to one anotherand represented in FIG. 1 solely by their axes. As can be seen moreclearly from FIGS. 3 and 4, each filter element 3 possesses a rightcross-section of outside shape that is hexagonal, for example, orcircular as in the example shown. Each filter element 3 comprises atleast one, and in the example shown, three channels 3 ₁ extendingparallel to the longitudinal axis of the filter element 3 so as to openout in each of its terminal portions 3 a and 3 b. The surface of eachchannel 3 ₁ is covered in at least one separating layer (not shown) thatis designed to come into contact with the fluid medium for processingthat flows inside the channel. The nature of the or each separatinglayer is selected as a function of the separation or filtering powerthat is to be obtained.

At each of their terminal portions 3 a, 3 b, the filter elements 3 aremounted on a support plate 4 which is fixed in leaktight manner to eachend of the case 2. In conventional manner, each support plate 4 has anumber of passages 5 equal to the number of filter elements 3 that aremounted inside the case 2. Each passage 5 is preferably of taperingshape with its smaller end opening to the inside of the enclosuredefined by the case 2. Each passage 5 enables a terminal portion of atubular filter element 3 to be positioned. Each passage 5 is designed tobe fitted with a sealing gasket 6 in accordance with the invention so asto ensure that the filter elements 3 are mounted in leaktight manner onthe support plates 4. Between themselves and the case 2, the supportplates 4 define a collecting enclosure 8 which communicates through atleast one outlet 9 for delivering the filtrate, i.e. the fluid mediumthat has passed through the filter elements 3. In conventional manner,each support plate 4 is designed to have mounted thereon by anyappropriate means a clamping backplate 11 that serves to deform thesealing gasket 6 in order to obtain good sealing.

As can be seen more precisely in FIGS. 3 to 5, each sealing gasket 6 isin the form of a sleeve of axial height h that is not less than theheight hps of the support plate 4. Thus, the sealing gasket 6 is capableof covering the filter element 3 over a length that is not less than theheight hps of the support plate 4. Under such conditions, the filterelement 3 cannot come into contact with the support plate 4 so thefilter element 3 is not subjected to friction or to erosion that mightlead to breakage thereof.

According to another characteristic of the invention, the sealing gasket6 has an overlap bore 15 for the filter element 3 which extends betweenone end 16 of the sleeve and a shoulder 17 which co-operates with theother end 18 of the sleeve to define a fluid-channeling bore 19. As canbe seen more clearly in FIG. 3, the shoulder 17 serves as an abutmentfor the general portion of the filter element 3. This shoulder 17presents a surface of dimensions that are adapted to extend outside thefree flow section Sc for the fluid. As can be seen more precisely inFIG. 4, each filter element 3 comprises at least one, and in the exampleshown, three flow channels 31 lying within the free flow section Sc. Inother words, this flow section Sc corresponds to the envelope containingall of the flow channels 3 ₁, such that a peripheral surface existsaround said section extending to the periphery of the filter element.Thus, the shoulder 17 presents dimensions that are adapted to extendoutside the flow section Sc of the filter element so as to avoidimpeding the flow of fluid flowing out from the channels 3 ₁.

According to a characteristic of the invention, the overlap bore 15possesses a determined height hp and a determined diameter dp.Considering that the diameter of the filter element 3 is equal to dm,the ratio of the diameter dp of the overlap bore over the diameter dm ofthe filter element lies in the range 0.6 to 1, and the ratio between theheight hp of the overlap bore 15 and the diameter dm of the filterelement 3 lies in the range 0.2 to 1.5.

According to another characteristic of the invention, the channel bore19 has a determined inside diameter dci and a determined inside heighthci. The inside height hci of the channel bore 19 lies between theinside diameter dci of the channel bore divided by 2 and the insidediameter dci of the channel bore divided by 24. Furthermore, the ratioof the inside diameter dci of the channel bore 19 divided by thediameter dm of the filter element 3 lies in the range 0.77 to 0.9.

According to a preferred embodiment characteristic, each sealing gasket6 possesses a determined outside diameter dce starting from the end 18into which the channel bore 19 opens out, this determined diameter dceextending over a determined height hce so as to form an outside collar21. Over its entire height, this collar 21 thus presents a diameter thatis constant. The ratio of the diameter dce of the collar 21 over thediameter dm of the filter element lies in the range 1.1 to 2.

According to a preferred embodiment characteristic, facing each passage5, each backplate 11 has a countersink 23 formed in that one of the mainfaces of the backplate 11 that faces the adjacent support plate 4. Eachcountersink 23 is in communication with a through hole 24 formed in thebackplate 11 and is adapted to receive a sealing gasket 6. Moreprecisely, each countersink 23 is designed to receive the gasket 6starting from its end 18 so as to receive at least part of the collar 21of the sleeve. According to an embodiment characteristic, the height hceof the outer collar 21 is such that the ratio of said height hce overthe height h1 of the countersink 23 lies in the range 1.5 to 10.

According to another characteristic of the invention, each sealinggasket 6 possesses on its outside, starting from the collar 21, a firstportion 25 of tapering shape and a second portion 26 of tapering shapeextending to the end 16 into which the overlap bore 15 opens out.

According to an embodiment characteristic, the first tapering portion 25possesses a maximum outside diameter dpc1ma, a minimum outside diameterdpc1mi and an outside height hpc1. The outside height hpc1 of the firsttapering portion 25 lies between the diameter dm of the filter elementdivided by 5 and the diameter dm of the filter element divided by 20.

According to another preferred embodiment characteristic, the ratiobetween the maximum outside diameter dpc1ma of the first taperingportion 25 over the diameter dce of the collar lies in the range 0.77 to1, while the ratio of the minimum outside diameter dpc1mi of the firsttapering portion 25 over the maximum outside diameter dpc1ma of thefirst tapering portion lies in the range 0.83 to 1.

According to another preferred embodiment characteristic, the secondtapering portion 26 possesses a maximum outside diameter dpc2ma equal tothe minimum outside diameter dpc1mi of the first tapering portion 25.This second tapering portion 26 also possesses a determined minimumoutside diameter dpc2mi and a determined outside height hpc2. The ratioof the diameter dp of the overlap bore 15 over the minimum outsidediameter dpc2mi of the second tapering portion 26 lies in the range 0.8to 1, while the ratio of the diameter hpc2 of the second taperingportion 26 over the diameter dm of the filter element 3 lies in therange 0.2 to 1.5.

According to another characteristic of the invention, the overlap bore15 has a groove 28 adjacent to the shoulder 17 in order to allow theconstituent material of the sealing gasket 6 to creep. Thus, when thebackplate 11 is clamped on the support plate 4, a portion of the gasketmaterial can creep into the inside of the groove 28 while notobstructing the flow section Sc of the filter element.

According to a preferred embodiment characteristic, the groove 28presents a determined diameter dg and a determined height hg such thatthe ratio of the groove diameter dg over the diameter dm of the filterelement lies in the range 1 to 1.5, while the ratio of the groove heighthg over the inside diameter hci of the channel bore 19 lies in the range0.2 to 1.

In the above example, each support plate 4 has a series of distinctindividual gaskets 6 each mounted in a respective passage 5. Accordingto another embodiment characteristic shown more particularly in FIG. 6,a series of sealing gaskets 6 for mounting on a support plate 4 can beinterconnected via connection zones 30 in such a manner as to constitutea single part. Each connection zone 30 possesses a determined height hmpsuch that the ratio hmp over the height hce of the collar 21 lies in therange 1 to 0.2.

The invention is not limited to the examples described and shown, sincevarious modifications can be applied thereto without going beyond theambit of the invention.

1. A sealing gasket for mounting in a passage (5) of a support plate (4)to surround the end of a tubular-shaped filter element (3) provided withat least one fluid flow channel (3 ₁), the channel lying within a flowsection Sc, the gasket being characterized in that it is made in theform of a sleeve: Possessing a height h not less than the height hps ofthe passage (5) in the support plate (4); and Presenting an overlap bore(15) for the filter element (3) defined between one end (16) of thesleeve and a shoulder (17) which co-operates with the other end of thesleeve to define a channel bore (19) for the fluid, the shoulder (17)possessing a surface for acting as an abutment for the terminal portionof the filter element and presenting dimensions that are adapted toextend outside the flow section Sc so as to avoid impeding fluidcirculation, the overlap bore (15) being provided with a groove (28)adjacent to the shoulder (17) in order to allow the gasket to creep. 2.A sealing gasket according to claim 1, characterized in that the groove(28) presents a diameter dg and a height hg such that the ratio dg/dmlies in the range 1 to 1.5 and the ratio hg/hci lies in the range 0.2 to1, with dm being the diameter of the filter element (3), and with hcibeing the height of the channel bore (19).
 3. A sealing gasket accordingto claim 1, characterized in that the overlap bore (15) possesses aheight hp and a diameter dp such that the ratio dp/dm lies in the range0.6 to 1, and the ratio hp/dm lies in the range 0.2 to 1.5, where dm isthe diameter of the filter element (3).
 4. A sealing gasket according toclaim 1, characterized in that the channel bore (19) possesses an insidediameter dci and an inside height hci lying in the range dci/2 to dci/24and such that the ratio dci/dm lies in the range 0.77 to 0.9.
 5. Asealing gasket according to claim 1, characterized in that the sleevepossesses on the outside, starting from the end (18) into which thechannel bore (19) opens out, a diameter dcc extending over a height hce,so as to form an outside collar (21), the ratio dce/dm lying in therange 1.1 to 2 and the ratio hce/hl lying in the range 1.5 to 10, wherehl is the height of a gasket-receiving countersink (23) formed in thebackplate (11) for fixing on the support plate (4).
 6. A sealing gasketaccording to claim 5, characterized in that the outside of the sleeve,starting from the collar (21), possesses a first tapering portion (25)and a second tapering portion (26) extending to its end (16) into whichthe overlap bore (15) opens out.
 7. A sealing gasket according to claim6, characterized in that: The first tapering portion (25) possesses amaximum outside diameter dpc1ma, a minimum outside diameter dpc1mi andan outside height hpc1 lying in the range dm/5 to dm/20, and such thatthe ratio dpc1ma/dce lies in the range 0.77 to 1, and the ratiodpc1mi/dpc1ma lies in the range 0.83 to 1; and The second taperingportion (26) possesses a maximum outside diameter dpc2ma equal to theminimum outside diameter dpc1mi of the first tapering portion (25) and aminimum outside diameter dpc2mi and an outside height hpc2 such that theratio dp/dpc2mi lies in the range 0.8 to 1, and the ratio hpc2/dm liesin the range 0.2 to 1.5.
 8. A multiple sealing gasket characterized inthat it comprises a series of gaskets (6) in accordance with claim 1interconnected by connection zones (30).
 9. A multiple sealing gasketaccording to claim 8, characterized in that the connection zones (30)are of a height hmp such that the ratio hmp/hce lies in the range 1 to0.2.
 10. A filter module of the type comprising at least one filterelement (3) supported at each of its terminal portions by a supportplate (4) provided with a passage (5) and having a backplate (11) fixedthereon, which backplate is provided with a countersink (23) for eachfilter element (3), the module being characterized in that for eachpassage (5) of the support plates (4), it includes a gasket (6) inaccordance with claim
 1. 11. A filter module of the type comprising atleast one filter element (3) supported at each of its terminal portionsby a support plate (4) provided with a passage (5) and having abackplate (11) fixed thereon, which backplate is provided with acountersink (23) for each filter element (3), the module beingcharacterized in that it includes a gasket (6) in accordance with claim1, fitted to each support plate (4).
 12. A filter module of the typecomprising at least one filter element (3) supported at each of itsterminal portions by a support plate (4) provided with a passage (5) andhaving a backplate (11) fixed thereon, which backplate is provided witha countersink (23) for each filter element (3), the module beingcharacterized in that it includes a multiple gasket in accordance withclaim 8 fitted to each support plate (4).